P-N junction scheme.

A place where two types of semiconductors touch, one p-type (with an excess of empty sites, or holes) and the other n-type (with an excess of free electrons). Thus, electric current can flow through a P-N junction in only one direction. The P-N junction is created by a doping process. The n-type material is enriched with an element that have an excess of easily displaced electrons, while the p-material is enriched with an element that offers an excess of vacancies, known as holes. P-N junctions are essential elements in the construction of diodes, transistors, solar cells, light-emitting diodes or integrated circuits.